In the power generation industry, an exciter is often positioned in axial alignment with a generator rotor which, in turn, is positioned in axial alignment with a turbine. The exciter is often a direct current ("DC") source and provides a current source to the generator rotor 20 through an axial lead (e.g., positive or negative) 22 positioned in an axial rotor bore 24 of the generator rotor body 21. As shown in prior art FIG. 1, an electrical path is provided to and from the axial lead 22 to coils 25 by two or more radial leads 26 which contact the axial lead 22 through radial bores 27 in the body 21 of the generator rotor 20 (see FIG. 1). The radial leads 26 are attached to the axial lead 22 by threads in the radial bores 27 and corresponding threads on the leads 22 themselves. A threaded spanner nut 30 positioned in a proximal portion of the radial bore 27 conventionally also assists in mounting the radial lead 26 to the axial lead 22. The radial lead 26 then connects to one of the coils 25 through a strap 29 which is secured to the radial lead 26 by a fastener assembly 28, and a current path is provided from the axial lead 22 through the radial lead 26, through the strap 29, and to the coils 25. Also, another portion of the coils 25 connects to another radial lead 26 which, in turn, again is connected to the axial lead 22 so that a positive to negative current path is established.
A hydrogen-cooled power generator within such a system often includes a housing which is sealed to prevent leakage of hydrogen gas positioned within the housing. The hydrogen gas is used to cool the generator. The hydrogen gas is conventionally at a much higher pressure within the housing than that of the atmospheric pressure outside the housing. If the hydrogen gas leaks from the housing, for example, the gas is potentially explosive and can cause various ventilation and environmental problems. The generator rotor is also positioned within the housing.
In addition to leakage from suspected locations or openings to and from the housing, other areas of the generator rotor are also susceptible to leakage such as through the axial lead, e.g., due to the pressure differential within and outside the housing. Access to the axial lead, for example, can be achieved by gas passing along outer peripheries of the radial bores. As shown in FIG. 1, to prevent such a leakage a complex sealing assembly 40 is conventionally used, including numerous sealing members, e.g., Chevron seals 42, and sealing hardware, e.g., washers 43, a spring 44, spacers 45. This complex assembly 40 is separate from the radial lead spanner nut 30, and can take extensive time and be costly to manufacture, can be complex to assemble and install, can be difficult to remove, and can be difficult to handle. For example, if portions of the sealing assembly 40 are not placed into position correctly the first time, then jamming within the radial lead bore 27 can occur. Also, the conventional sealing assembly 40, for example, requires an axial load applied by the spring 44 in order to activate the seals.